This study will attempt to meet the following objectives: 1. To develop permanent endothelial cell strains from single cell clones. 2. To isolate and identify an epidermal angiogenic factor from postembryonic rabbit skin. 3. To isolate and characterize the Weibel-Palade body from postembryonic rabbit skin endothelial cells. 4. To determine the role of injury to the stratum corneum in the synthesis of the epidermal angiogenic factor. 5. To determine the mechanism of action of the epidermal angiogenic factor beginning with a study of RNA and protein metabolism in endothelial cells.